Android 5.0 - external SD Card write protected.

On my Son's kindle, I loaded the sandisk app, and set the download directory for a video directory I added to the external sd card:

/storage/sdcard1/Video

And that doesn't work.

I know that when i used a file manager (ES File Explorer) to create the video directory on the SD card, it said that as of Android 5.0 SD cards were now write protected, and that you had to select the root directory from a special android dialog to give the app permission to write to the card...

So...

I can download files from the flash drive to internal memory, then use ES file explorer to copy the file to the SD card, but it would be much easier if the SanDisk app would ask for and receive my permission to directly download into the external SD card...